Acetylene solution



2,199,365 ACETYLENE SOLUTION No Drawing. Application May 17, 1954,Serial No. 430,415

12 Claims. (Cl. 183115) assignor to Monsanto a corporation of Thisinvention relates to acetylene and more specifically to acetylenesolutions. This invention also relates to the recovery' of acetylenefrom an acetylene-containing gas by means of a selective solvent.

It is known in the art that various organic compounds have shown utilityas selective solvents for acetylene, thereby affording means for storingacetylene in the form of solutions of acetylene in the solvents andmeans of extracting acetylene from gas mixtures or increasing theacetylene content of such gas mixtures.

It is an object of this invention to provide a class of solvents havingexceptional utility in the aforementioned applications. Other. objectswill become apparent from the description of the invention.

It has now been discovered that derivatives of phosphonic acid havingthe formula wherein R1 is an alkyl group containing from 1 to 3 carbonatoms, R2 is a B-dialkylaminoethoxy or an alkoxy group in which thealkyl groups contain from 1 to 3 carbon atoms, and R3 is a,B-dialkylaminoethoxy group in which the alkyl groups contain from 1 to3 carbon atoms are excellent solvents for acetylene.

The Bunsen coeflicients (volume of gas, measured at C. and 760 mm. Hg,dissolved, at the'temperature of the experiment, in one volume ofsolvent at a gas partial pressure of 760 mm. Hg) for acetylene in thesesolvents indicate their excellent solvent action for acetylene. TheBunsen coeflicients (d were determined in the following manner:

A quantity of acetylene was introduced into a calibrated flask and itsinitial pressure p (measured to 10.05 mm. Hg), initial volume V1(measured to $0.05 ml.), and initial temperature T1 (measured to :0.02C.) determined. A quantity of solvent was then added to a secondcalibrated flask and its volume ml and vapor pressure Ps determined. Theacetylene was then transferred to the flask containing the solvent and,after agitation, the temperature of the liquid was brought to atemperature of 25:0.005 C. and the temperature of the gas was brought toa temperature of 25.3":005 C. The pressure of p of the gas, volume Vi ofthe gas and temperature Tt of the gas were then determined. d was thencalculated as follows:

a: 2732 pi i (Pf Pa) i) 760 ml, T Z; T -Z; where pf pltrite StatesPatent C "ice d,=density of solvent at 25 C.

where M W,.=molecula.r weight of solvent Bis (fiedicthylaminoethyl)ethanephosphonate Ethyl (fi-dimethylaminoethyl) methanephosphonate Bis(fl-dimethylaminoethyl) propanephosphonate Methyl (fi-diethylaminoethyl)methanephosphonate Propyl .(p-dipropylaminoethyl) ethanephosphonateAccording to this invention, these solvents are most efficiently .usedin the extraction of acetylene from diluted acetylene such as isobtained by the partial oxidation of low molecular weight hydrocarbons.As an example, dilute acetylene obtained from the partial oxidation ofmethane with oxygen has the following composition:

Percent C2H2 8.5 Hz 51.4 N2 1.6 CO 26.3 CH4 5.8 CO2 5.9 C2H4 0.1 Heavieracetylenes 0.4

This gas stream is treated under pressure with the aforementionedsolvents in any convenient manner well known to those skilled in the artas, for example, by countercurrent absorption in a suitable solvent. Thesolution of acetylene is then transferred to a suitable desorptioncolumn where the pressure is released and the temperature raised.Concentrated acetylene is thus obtained and any contamination of theacetylene with the solvent is so small as to be insignificant.

In addition to the utility of these solvents in the extraction ofacetylene from diluted acetylene, the Bunsen COCfllClfiIltS of thesesolvents clearly indicate that they are particularly suited for storingacetylene under elevated pressures.

The solvents described herein may be used per se, or they may be used inmixtures with other acetylene solvents.

The term consisting essentially of which appears in the claims hereof isintended to refer to a composition in which the total amounts of thecomponents set forth in the claim constitute the predominant proportionin the composition. Such term is not intended to exclude the presence ofmaterials such as moisture or water, or other material which may bepresent as an inert diluent and does not adversely affect the solutionin any manner. However, the term is intended to exclude the presence ofmaterials which so change the character of the composition that it canno longer be regarded as a solution of acetylene.

wherein R1 represents an alkyl radical having from 1 to 3 carbon atoms,R represents a radical chosen from the group consisting of alkoXy andfl-dialkylaminoethoxy radicals in which the alkyl groups contain from 1to 3 carbon atoms, and R3 represents a fi-dialkylaminoethoxy radical inwhich the alkyl groups contain from 1 to 3 carbon atoms.

2. A composition of matter consisting essentially of a solution ofacetylene in bis(B-dirnethylaminoethyl) methanephosphonate.

3. A composition of matter consisting essentially of a solution ofacetylene in isopropyl fl-dimethylatninoethyl methanephosphonate.

4. A composition of matter consisting essentially of a solution ofacetylene in bis(/3-diethylaminoethyl)- ethanephosphonate.

5. A composition of matter consisting essentially of a solution ofacetylene in ethyl fi-dimethylaminoethyl methanephosphonate.

6. A composition of matter consisting essentially of a solution ofacetylene in bis(B-dimethylaminoethyl) propane phosphonate.

7. In a process for the recovery of acetylene from acetylene-containinggas, the steps of contacting said gas with a derivative of phosphonicacid having the formula wherein R1 represents an alkyl radical havingfrom 1 to 3 carbon atoms, R2 represents a radical chosen from the groupconsisting of alkoxy and p-dialkylaminoethoxy radicals in which thealkyl groups contain from 1 to 3 carbon atoms, and R3 represents afi-dialkylaminoethoxy group in which the alkyl groups contains from 1 to3 carbon atoms.

8. In a process for the recovery of acetylene from acetylene-containinggas, the step of contacting said gas with his(fi-dimethylaminoethyl)methanephosphonate.

9. In a process for the recovery of acetylene from acetylene-containinggas, the step of contacting said gas with isopropylfl-dimethylaminoethyl methanephospho nate.

10. Ina process for the recovery of acetylene from acetylene-containinggas, the step of contacting said gas with his (fi-diethylaminoethyl)ethanephosphonate.

11. In a process for the recovery of acetylene from acetylene-containinggas, the step of contacting said gas with ethyl ,B-dimethylaminoethylmethanephosphonate.

12. In a process for the recovery of acetylene from acetylene-containinggas, the step of contacting said gas with bis(fi-dimethylaminoethyl)propane phosphonate.

References Cited in the file of this patent UNITED STATES PATENTS2,623,611 Levine et a1 Dec. 30, 1952

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF
 1. A PROCESS OFCONTINUOUSLY CASTING METAL BARS, BILLETS A SOLUTION OF ACETYLENE IN ADERIVATIVE OF PHOSPHONIC ACID HAVING THE FORMULA OR THE LIKE, COMPRISINGSUBJECTING THE MOLTEN METAL TO THE COMBINED ACTION OF GAS UNDER STATICPRESSURE AND